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November 21, 2017

Can Sleep Apnea Increase The Risk of Alzheimer's Disease?

A new research study suggests that elderly people dealing with obstructive sleep apnea (OSA) may have an increased risk of developing Alzheimer's disease (AD). The study, which was recently published in the American Thoracic Society's American Journal of Respiratory and Critical Care Medicine, examined OSA due to previous research suggesting that it might accelerate cognitive decline in people at risk for AD. According to lead researcher Ricardo S. Osorio, MD, assistant professor of psychiatry at New York University School of Medicine, proving a causal link has been difficult up to now since OSA and AD often share risk factors and commonly coexist.

The study examined 208 participants aged 55 to 90 using a series of clinical tests including sleep testing to monitor breathing while they slept. None of the participants had been previously diagnosed with OSA or had other medical conditions that might have affected study results. Results showed that more than half of the participants had some form of OSA with 16.8 percent having moderate to severe breathing problems at night.

Of these, 104 participants then took part in a two-year study that included undergoing lumbar punctures to obtain cerebrospinal fluid (CSF) as well as PET scans to measure amyloid beta plaque deposits in the brain. Amyloid beta is a peptide that has been implicated in the development of cognitive problems linked to dementia. Research findings showed a significant correlation between OSA severity and decreased amyloid beta peptides in the CSF over time as well as increased amyloid deposits in the brain.

Surprisingly enough however, OSA doesn't appear to predict cognitive deterioration in healthy adults. According to study coauthor Andrew Varga of the Icahn School of Medicine at Mount Sinai in New York, the measures use may not pick up on the very subtle cognitive changes often found in the very early stages of AD. As for cognitive changes that can be detected, there is no reliable way of telling them apart from the cognitive problems linked to lack of sleep.

Though much more research is needed, these results suggest that standard OSA treatments such as CPAP, dental appliances, and positional therapy may help delay dementia in older adults. "Results from this study, and the growing literature suggesting that OSA, cognitive decline and AD are related, may mean that age tips the known consequences of OSA from sleepiness, cardiovascular, and metabolic dysfunction to brain impairment," Dr. Osorio said in a recent interview. "If this is the case, then the potential benefit of developing better screening tools to diagnose OSA in the elderly who are often asymptomatic is enormous."

Considering that AD and other forms of dementia already affect millions of people worldwide, a number that will certainly increase as Baby Boomers grow older, finding better ways of helping patients cope with memory loss can play a critical role in future health care.